Asian Journal of Medical Sciences 4(2): 99-102, 2012
ISSN: 2040-8773
© Maxwell Scientific Organization, 2012
Submitted: March 12, 2012
Accepted: March 26, 2012
Published: April 30, 2012
Detection of Legionella from Teaching Hospital Cooling Tower Water of Air
Conditioning Systems in Eastern Province of Saudi Arabia
1
Nasreldin Elhadi and 2Hatem Qutub
Department of Medical Laboratory Sciences, College of Applied Medical Sciences,
2
Department of Internal Medicine, College of Medicine, University of Dammam, Dammam,
Saudi Arabia
1
Abstract: The objective of this study was to investigate the frequency of contamination of Legionella in the
King Fahd Hospital of the University (KFHU) cooling tower water of air conditioning system and other water
supplies. A total of 300 samples were collected from various sites in KFHU. Water samples were collected from
the cooling tower (88), hot-shower head (40), cold-shower head (59), engineering building (12) and drinking
fountain (12). Swab samples were also collected from shower heads (44) and air ventilator (45). Overall
Legionella was detected in only 5 (5.68%) out of 88 water samples and yielded 7 isolates. All other water
samples that were collected from other sites were negative for the presence of Legionella. Culturing the hospital
water supply for Legionella was the first step in the assessment of the risk for hospital-acquired Legionnaires’
(LD). Legionella is a common cause of hospital-acquired pneumonia, especially for immunocompromised
patients.
Key words:Cooling tower water, Eastern Province of Saudi Arabia, King Fahd Hospital of the University,
Legionella
inhalation of aerosols generated from water sources
(Leoni et al., 2005). Legionnaires’ disease is known to
cause hospital acquired pneumonia and may occur as part
of an outbreak or sporadically (Yu, 2003). Between 1980
and 2002, 4402 cases of Legionnaires’ disease were
identified in England and Wales, of which 264 were
hospital acquired (Cooke et al., 2004). The proportion of
hospital acquired pneumonia due to Legionella has been
reported as ranging from 0 to 47% (Hutchinson, 1990).
The incidence of hospital-acquired legionellosis is
underestimated for a variety of reasons, including a lack
of clinical awareness or a missed diagnosis, e.g. nonclassical presentation especially in very ill or
immunocompromised patients, infection at sites other
than the respiratory tract, including soft tissue infections
(Hart and Makin, 1991) and endocarditis, (Johnson et al.,
1985) delayed seroconversion, or lack of specialized
culture facilities or urinary antigen detection tests in
diagnostic microbiology laboratories. It has been shown
that when an active search for legionella infection is
initiated, cases are frequently confirmed (Hutchinson,
1990). Forty-eight different species of Legionella have
been identified to date, although less than half of these
have been linked to disease in human (Stout and Yu,
1997). Thus, this the first study to investigate the
frequency of Legionella contamination in hospital water
systems in Eastern Province of Saudi Arabia, with a
INTRODUCTION
Legionella is a facultative intracellular pathogen
known to cause both community and hospital acquired
pneumonia (Fields et al., 2002; Sabria et al., 2004). The
genus Legionella pneumophila accounts for 90% of cases
of legionellosis, (Joseph, 2004) and about 85% are due to
serogroup (Grove et al., 2002) other Legionella spp. are
rarely pathogenic in humans (Doleans et al., 2004).
Community-Acquired Pneumonia (CAP) is commonly
defined as an acute infection of the pulmonary
parenchyma that is associated with at least some
symptoms of acute infection, accompanied by the
presence of an acute infiltrate on a chest radiograph or
auscultatory findings consistent with pneumonia, in a
patient not hospitalized or residing in a long-term care
facility for 14 days before onset of symptoms (Bartlett
et al., 2000).
In recent years, nosocomial Legionnaires’ disease has
been on the increase (Chien et al., 2004). Although cases
of nosocomial Legionella pneumonia are increasingly
recognized, there is no general consensus regarding the
prevention of legionellosis in hospitals. The Centers for
Disease Control and prevention (CDC) only recommend
routine environmental investigation in water samples from
high risk wards housing transplanted patients (Tablan
et al., 2004). Legionella infection occurs mainly by
Corresponding Author: Nasreldin Elhadi, Department of Medical Laboratory Sciences, College of Applied Medical Sciences,
University of Dammam, P.O. Box 2435, Dammam 31451, Saudi Arabia, Tel.: + 966 3 8577 000 ext.
2751
99
Asian J. Med. Sci.,4(2): 99-102, 2012
Water samples were filtered and concentrated in a
biological safety cabinet by pouring the samples into a
sterile 47 mm filter funnel assembly containing a 0.2 :m
polycarbonate filter and were connected to a vacuum
source. All water samples were allowed to pass through
the filter and the filter papers were removed aseptically
from the holder with sterile forceps. The filter studyies
were folded and placed into a sterile 50 mL centrifuge
tube containing 5 mL of sterile water. The centrifuge
tubes were vortex for one 1 min to free bacteria and other
organic material from the filter studies. (1.0 mL) of the
vortex suspension were placed into a sterile 15 mL
centrifuge tube containing 1.0 mL of acid buffer (acid
treatment) and incubated for 15 min at room temperature.
(0.1 mL) of the suspension were spread onto Buffered
Charcoal Yeast Extract (BCYE) agar containing 0.1%
alpha-ketoglutarate is the base medium used for the
recovery of Legionella from environmental and clinical
specimens. All plates were incubated at 35ºC for 3 to 10
days and examined for growth every 24 h.
Fig. 1: Cooling tower water system
Identification and confirmation: Suspect colonies were
sub-cultured in parallel onto BCYE and blood agar plate
media and incubated at 35ºC for another 3 to 4 days. The
presence of growth on BCYE agar and absence of growth
on blood agar plate suggested Legionella species.
Legionella species were further confirmed by using
hippurate hydrolysis test and were tested with a latex test
(Oxoid Ltd, Basingstoke, UK).
Fig. 2: Water inside the cooling tower
RESULTS AND DISCUSSION
purpose to understand the extent of Legionella
contamination in the cooling tower water of air
conditioning system.
A total 5 (1.66%) out 300 water samples and swabs
samples were found to be positive for Legionella. These
samples were collected from different sites and wards in
King Fahd hospital of the University (Table 1). In this
study Legionella were detected only from water samples
collected from cooling towers which yielded a total of 7
isolates. Hospital-acquired LD has rarely been reported
from Saudi Arabia and environmental cultures of
Legionella in hospitals water systems in Saudi
Arabia have never been systematically performed. To our
MATERIALS AND METHODS
Sampling: This study was conducted in November, 2009
in King Fahd Hospital of the University of Dammam. A
total of 300 samples were collected from cooling tower
water system (88), swab from shower head (12), hotshower head (40), cold-shower head (59), engineering
building (12), drinking fountain (12) and air ventilator
(45). A volume of 500 mL of water was collected
immediately after opening the valve from each of
sampling site (cooling towers, drinking fountain, cold and
hot showers, and engineering building) as shown in
Fig. 1 and 2. Swabs samples also were collected from
ventilation units, air humidifiers and hot and cold
showers.
Table 1:Surveillance of legionella in King Fahd Hospital of the
University (KFHU)
Source of water
No. of positive
samples
No. of samples
samples (%)
Cooling towers
88
5 (5.68%)
Shower heads (hot)
40
0
Shower heads (cold)
59
0
Swabs from shower heads
44
0
Engineering building
12
0
Drinking fountain
12
0
Air ventilator (swabs)
45
0
Total
300
5 (1.66%)
Microbiological processing of water samples: Water
samples were processed according to the Centers for
Disease Control and prevention (2005) (CDC) procedures
for the recovery of Legionella from the environment.
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Asian J. Med. Sci.,4(2): 99-102, 2012
knowledge, there was no documented epidemiological
investigation in Saudi Arabia to determine the origin and
sources of this organism. Legionella was found in 5.68%
out 88 water samples of KFHU water systems in Eastern
Province of Saudi Arabia. Cases of hospital-acquired
Legionnaires’ disease may have occurred in Eastern
Province of Saudi Arabia but not been detected. This
study recommends that the KFHU infection control unit
consider mandating environmental surveillance of
Legionella not only for KFHU but for all hospitals in
Eastern province of Saudi Arabia, as is now implemented
in many European countries (Anonymous, 2005) and
elsewhere (Lin and Yu, 2006; Stout et al., 2007).
Hospital water systems are the primary reservoirs for
hospital-acquired Legionnaires’ disease (Farr et al.,
1988). Prevention of hospital-acquired LD has been
accomplished by disinfecting hospital water system (Best
et al., 1983; Lin et al., 1998). To our knowledge no
hospital in Eastern Province routinely cultures their water
distribution system for Legionella; this policy was
adopted following the discovery of the first case of
hospital-acquired LD that was epidemiologically linked to
the hospital water distribution system, not the cooling
towers (Patterson et al., 1997). Prevalence and surveys of
Legionella colonization in hospitals have been conducted
and reported in in the UK, (Patterson et al., 1997), Canada
(Alary and Joly, 1992; Marrie et al., 1994), USA (Vickers
et al., 1987) and Spain (Sabria et al., 2004).
Cooling towers were originally thought to be the
main reservoir for Legionella, but subsequent reports have
identified the water distribution systems as the major
source of LD in hospitals (Joseph et al., 1994). Culturing
the hospital water supply for Legionella is the first step in
the assessment of the risk for hospital-acquired LD. This
approach is widely adopted in the national guidelines
(Anonymous, 2005) for France, Denmark, Germany,
Netherlands, Spain, Italy, Norway, Portugal and
Switzerland and in other regional guidelines and
recommendations (Anonymous, 1997). Environmental
surveillance for Legionella in hospital water supplies can
provide significant data that are useful for prevention of
hospital-acquired LD. However, this the first study was
conducted the first environmental surveillance of King
Fahd Hospital of the University (KFHU) in Eastern
Province of Saudi Arabia.
important strategy in prevention whereas an application of
copper-silver ionization systems has emerged as the most
successful long-term disinfection method for the hospital
water systems (Stout and Yu, 2003).
ACKNOWLEDGMENT
This research study was supported by University of
Dammam from the Deanship of Scientific Research. The
authors would like to thank the Microbiology Laboratory
technicians (Mr. Lauro Bartolome, Mr. Piodennis Dasal
and Mr. Bader Sager) for their contribution.
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